1. Field of the Invention
The present invention relates to a communication apparatus and communication method for transmitting a content, and a recording medium storing a program.
2. Description of the Related Art
With the spread of network data communications over the Internet, a Local Area Network (LAN), etc., many households connect their electric appliances, computers, and other peripheral devices installed in their home to a network to use a home network that allows the devices to communicate.
For example, the Digital Living Network Alliance (DLNA) advocates a seamless network system that provides interoperability among any variety of electric appliances to enable one to enjoy a content from any of the appliances easily and conveniently at any place in the home. This system allows information such as an Audio Visual (AV) content that is stored on any device on the network to be received from any of the devices on the network. Accordingly, there is no need of caring about where a content is stored, and it is possible to view or listen to a content stored on a device that is installed in a separate room while staying in a different room. Therefore, usefulness is increased.
Further, as an extended version of the DLNA, a system that enables a domestic DLNA environment to be used un-domestically is also being studied. According to this technique, a plurality of devices are connected via the Internet according to a Session Initiation Protocol (SIP), and a router that functions as gateware that intermediates between the DLNA and the SIP is installed in the home. Hence, once the router in the home is authenticated successfully, it becomes a virtual DLNA device, which can be controlled by the real DLNA device in a remote place.
As more devices become DLNA-enabled and networking-enabled in the future, it is presumed that plural pieces of communication data may jam the network. In particular, in a case where many unidentified users access home-equipped DLNA devices from outside to send or receive a content, plural pieces of communication data compete for and thus run short of the communication band, and cause problems such as a delay in the distribution of streaming data that allows no delay.
As a method for solving such a problem, Unexamined Japanese Patent Application KOKAI Publication No. 2005-130150 discloses a method that allocates more resources to priority data to improve the communication quality of the priority data based on a priority Quality of Service (QoS) technique. The DLNA guideline also provides wired LAN 802.1D, which is a QoS scheme based on band reservation, and wireless LAN Wi-Fi Multimedia (WMM) as options to propose a system that can prevent a collapse of streaming data distribution that might occur due to a lack of the communication band.
Even the method described in Unexamined Japanese Patent Application KOKAI Publication No. 2005-130150 may be neither able to guarantee the communication quality nor hence able to maintain a fine communication environment when a plurality of streaming distribution sessions are held in parallel. For example, in a case where a plurality of (“n” number of) contents that are set to the same priority degree are streaming-distributed in parallel, if there is no sufficient network band available for transmitting the “n” sequences of streaming data, none of the “n” sequences of streaming data can be maintained at a transfer rate sufficient for them to be reproduced on the client side in real time, causing communication failures on the client device, such as disorders in the reproduced images, sound interruptions, etc.